1. Field of the Invention
The present invention relates to a push-type vehicle switch mainly used for lighting control of a stop lamp when operating a brake pedal of an automobile.
2. Background Art
In recent years, a large number of push switches that works by pressing have been used for lighting control of a stop lamp in a vehicle when operating a brake pedal of an automobile. A description is made for such a conventional push-type vehicle switch with reference to FIG. 7. FIG. 7 is a sectional view of the conventional push-type vehicle switch.
Case 1, made of insulating resin, is substantially tubular with its top surface open. Actuating shaft 2 is contained in case 1 movably up and down. Case 1 has a plurality of fixed contacts 3 implanted therein with terminals 3A projecting beyond a bottom surface thereof. Movable contact 4, made of metal, is pressed against fixed contacts 3 from below by press contact spring 5 that is attached between movable contact 4 and the bottom surface of case 1 in a slightly pressed state. Fixed contacts 3 are electrically connected with each other through movable contact 4. A switch contact is thus formed.
Return-spring 6 is attached between a bottom surface of actuating shaft 2 and the bottom surface of case 1 in a slightly pressed state, to bias actuating shaft 2 upward. Operation portion 2A, at the top end of actuating shaft 2, projects upward through a through-hole provided in the center of cover 7 covering the opening on the top surface of case 1. In this way, a push-type vehicle switch is composed.
A push-type vehicle switch thus composed is generally attached before the brake pedal of an automobile, with operation portion 2A being pressed on an arm (not illustrated). Then terminal 3A of fixed contact 3 is connected to the stop lamp with a connector or the like.
With the brake pedal not being depressed by a driver, operation portion 2A is pressed downward by the arm, press contact spring 5 and return-spring 6 are pressed, and movable contact 4 moves downward to separate from fixed contacts 3. Consequently, fixed contacts 3 are electrically disconnected and the stop lamp remains turned off.
With the brake pedal depressed, the arm separates from operation portion 2A to remove the pressing force, and thus actuating shaft 2 moves upward owing to the elastic return force of return-spring 6. At this moment, movable contact 4 is pressed by press contact spring 5 to be pressed against fixed contacts 3, causing fixed contacts 3 to be electrically connected with each other. This action turns on the stop lamp. Such a push switch is disclosed in Japanese Patent Unexamined Publication No. 2001-297654, for example.
However, such a switch is usually used near the brake pedal, exposed to lubricating oil, a relatively large amount of dust, and the like. Therefore, it is required to prevent these undesired substances from entering the switch through the clearance between case 1 and cover 7, actuating shaft 2 and cover 7 at the through-hole, and the like. In order to improve resistance against oil and dust, the entire switch is covered with a rubber cover, or the clearance between case 1 and cover 7 is sealed with an adhesive or the like. Consequently, the switch is difficult to assemble and needs a relatively long manufacturing time.